Millions of dollars in negative television advertising from super PACs supporting Gingrich rivals has aired in Iowa and voila: four Iowa opinion surveys released since Wednesday show a precipitous plunge in Gingrich’s support.

Super PACs can raise and spend unlimited amounts of money on behalf of a candidate but cannot coordinate or be in contact with a candidate’s campaign.

To some in politics, the cause and effect is obvious. David Axelrod, a top strategist for the Obama re-election campaign, drew a straight line between the two, via Twitter.

“Today’s polls reflect the devastation inflicted on Gingrich by pro-Romney Super PAC, which has nuked Newt with millions in negative ads,” he said shortly after a CNN poll was released late Wednesday. The poll showed Gingrich in fourth place in Iowa.